First off, timing has to be set regardless of the HC results. It does not
make sense for two reputable shops to set ignition timing and yet the
vehicle still fail the timing inspection at a smog station or test only
center. Someone doesn't know how to set timing properly, or the smog station
doesn't know how to check timing properly. Either way before you can
diagnose the high HC fault you have to ensure ignition timing is set exactly
where Honda requires it to be set. Next... HC can be caused by many things.
Number 1 is ignition related. Sparkplugs and spark wires are constantly
exposed to high temperatures and high voltage. You must ensure your engines
ignition system is functioning properly by inspecting all sparkplugs, their
wires, distributor, distributor cap, and rotor.
If you've inspected the ignition system and found no faults, you want to
then look at the other emissions numbers; specifically CO. CO is Carbon
Monoxide, it is partially burned fuel. If on your smog test result you see
CO is high, this is an indication of a rich misfire. You want to then
diagnose the fuel feedback system. If CO is too low, this is an indication
of a lean misfire, and you need to look into the fuel feedback system, as
well as any problem which may restrict fuel flow.
